Down-regulation of TSC-22 (transforming growth factor beta-stimulated clone 22) markedly enhances the growth of a human salivary gland cancer cell line in vitro and in vivo.
We have recently isolated TSC-22 (transforming growth factor beta-stimulated clone 22) cDNA as a new anticancer drug (Vesnarinone)-inducible gene in a human salivary gland cancer cell line, TYS. We conducted the present study to examine whether up-regulation or down-regulation of TSC-22 can affect the growth of TYS cells in vitro and in vivo. We constructed an expression vector containing sense- or antisense-oriented human TSC-22 cDNA under the transcriptional control of the SR alpha promoter. We cotransfected TYS cells with the sense or antisense expression vector and pSV2neo and obtained more than 200 G418-resistant colonies in each sense or antisense transfectant. Approximately 80% of representative G418-resistant clones expressed the transcripts from transfected sense or antisense TSC-22 cDNA. To avoid the clonal heterogeneity of the cells, we mixed all of the G418-resistant colonies together in each sense or antisense transfectant and examined the expression of TSC-22 protein, in vitro growth, and the tumorigenicity in nude mice. The expression of TSC-22 protein was examined by solid-phase ELISA using a specific antibody against recombinant TSC-22 protein. The expression of TSC-22 protein was up-regulated in the sense transfectants and down-regulated in the antisense transfectants. Contrary to our expectation, up-regulation of TSC-22 protein did not affect both in vitro and in vivo growth of TYS cells. However, down-regulation of TSC-22 markedly enhanced the growth of TYS cells in vitro and in vivo. Furthermore, we examined the expression of TSC-22 mRNA in several human salivary gland tumors. The mRNA expression of TSC-22 in benign and malignant salivary gland tumors was significantly decreased when compared to that in tumor-free salivary glands (P < 0.05; one-way ANOVA), and in some salivary gland tumors, the expression of TSC-22 mRNA was not detectable by reverse transcription-PCR. These results suggest that down-regulation of TSC-22 may play a major role on salivary gland tumorigenesis.
Nakashiro
K
K
Second Department of Oral and Maxillofacial Surgery, Tokushima University School of Dentistry, Japan.
Kawamata
H
H
Hino
S
S
Uchida
D
D
Miwa
Y
Y
Hamano
H
H
Omotehara
F
F
Yoshida
H
H
Sato
M
M
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D002999:Clone Cells; D016373:DNA, Antisense / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D016350:Leucine Zippers / Q000235:genetics; D051379:Mice; D008819:Mice, Nude; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D009368:Neoplasm Transplantation; D011401:Promoter Regions, Genetic; D011719:Pyrazines; D011804:Quinolines / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D012334:RNA, Neoplasm / Q000096:biosynthesis; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics; D012097:Repressor Proteins; D012468:Salivary Gland Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured
D000970:Antineoplastic Agents; D016373:DNA, Antisense; D018076:DNA, Complementary; D009363:Neoplasm Proteins; D011719:Pyrazines; D011804:Quinolines; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; C099726:TSC22D1 protein, human; C490983:Tgfb1i4 protein, mouse; D014157:Transcription Factors; C041667:vesnarinone